DOCSLIB.ORG

The Early Toarcian Environmental Crisis and Oceanic Anoxic Event

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Early Toarcian Environmental Crisis and Oceanic Anoxic Event Paleo-ecosystems: Early Toarcian environmental crisis The Early Toarcian environmental crisis and oceanic anoxic event (Early Jurassic; 183 Ma BP) Paleo-ecosystems: Early Toarcian environmental crisis Oceanic anoxic events (OAE): OAEs represent periods in Earth’s history that were highlighted by widespread organic matter burial, associated with anoxia and/or euxinia at a global scale. The Early Toarcian OAE represent the first of series of OAEs documented throughout the Jurassic and Cretaceous (Jenkyns, 2010). OAEs were often accompanied by (global) climate perturbations and extinction events. Paleo-ecosystems: Early Toarcian environmental crisis In the sedimentary record the Early Toarcian event is expressed by the widespread accumulation of organic matter-rich sediments. Those have been intensively studied throughout Europe (Germany: Posidonia Shale; France: Schistes Carton; UK: Jet Rock). Early Toarcian bituminous sediments have a thickness of 10 to 40 m and have been deposited within 1 to 1.5 Myr. At some locations black shale deposition lasted longer than 2 Myr. Due to high concentrations of organic matter and the wide spatial and stratigraphic extent, Early Toarcian black shales can be important sources rocks (e.g. North Sea, Central Paris Basin). Paleo-ecosystems: Early Toarcian environmental crisis Toarcian bituminous sediments are famous for their excellent fossil preservation. Remains of mainly nektonic organisms can be extremely enriched in distinct horizons, suggesting slow sediment accumulation rates in combination with a low-energetic depositional environment. Paleo-ecosystems: Early Toarcian environmental crisis extinction level glacial deposits? glacial K-F global warming carbon cycle sea level OAE LIP (icehouse-greenhouse transition?) perturbation rise Paleo-ecosystems: Early Toarcian environmental crisis Global paleogeographic reconstruction of the Earth during the Early Toarcian (approx. 183 Ma BP) (Blakey, “Global Paleogeography and Techtonics in Deep Time © 2016 Colorado Plateau Geosystems Inc.”). Shelf areas were bituminous sediments have been accumulated were marked in yellow. The Toarcian CIE has been documented from locations around the globe attesting to a global perturbation of the carbon cycle. Paleo-ecosystems: Early Toarcian environmental crisis Jurassic climate conditions Paleo-ecosystems: Early Toarcian environmental crisis The Jurassic as well as the Cretaceous have been commonly associated with overall warm climate conditions during a long-lasting greenhouse mode (Frakes et al., 1992). A low equator-pole temperature gradient has been associated with ice-free polar regions. Paleo-ecosystems: Early Toarcian environmental crisis The assumption of an overall ice-free Jurassic world was mainly based on floral and faunal distribution patterns. The occurrence of vegetation adopted to warm temperate climates at high latitudes has been used as evidence for warm (subtropical) climates at polar regions. Analysis of floral provinces provides only a superficial view on climate conditions, summarizing warm and cold climate conditions over a period of several tenth of millions of years. e.g. Early Jurassic: 201 – 174 Ma BP (GTS 2012) Paleo-ecosystems: Early Toarcian environmental crisis Jurassic climate ups and downs – cold (ice-house) – green (hot-house) cycles? Paleo-ecosystems: Early Toarcian environmental crisis A B Glacial-derived deposits of Early Jurassic (Pliensbachian) age have been reported from Siberia as well as from Europe (e.g. Suan etal., 2011; Teichert & Luppold, 2013). A) glendonites: calcite pseudomorphs (CaCO3 x 6H2O), formation requires tempertures below 4°C, but might also be associated with methane seeps B) boulder rocks: large blocks in a fine-grained sedimetn matrix, typically associated with ice-related transport. Paleo-ecosystems: Early Toarcian environmental crisis Climate evolution across the Pliensbachian-Toarcian boundary and throughout the Early Toarcian, inferred from belemnite oxygen isotope data, stomata-indices, floral- characteristics, GDGT-based air temperature reconstructions and sedimentological features (glacial-derived deposits, glendonites). Data are from numerous sources. Paleo-ecosystems: Early Toarcian environmental crisis Timing of the Karoo-Ferrar volcanism Paleo-ecosystems: Early Toarcian environmental crisis Toarcian warming Pl-Toa warming Correlation of peak activity phases of Karoo-Ferrar volcanism with the Early Toarcian climate change. Data are from numerous sources. Paleo-ecosystems: Early Toarcian environmental crisis Early Toarcian extinction event(s) Paleo-ecosystems: Early Toarcian environmental crisis The Early Toarcian extinction event in a wider context. The Early Toarcian environmental crisis was associated with profound environmental changes as well as with drastic climate perturbations (pCO2 x 3; 4-6°C rise in SST). However, high extinction rates were mainly documented for benthic taxa, while nektonic organisms experienced high turnover rates. Paleo-ecosystems: Early Toarcian environmental crisis The Early Toarcian environmental crisis is associated with multiple extinction events that affected invertebrates and primary producers. Paleo-ecosystems: Early Toarcian environmental crisis Changes in the species diversity of ammonites from sections from Europe and N-America. A diversity loss has been documented in the kanense zone (time-equal to the D. tenuicostatum and H. serpentinum zones). Also shown extinction and origination rates for ammonites and foraminifera. Data from Caruthers et al. (2013) and references therein. Paleo-ecosystems: Early Toarcian environmental crisis High extinction rates were documented for benthic communities that suffered from declining oxygen levels in bottom waters across the shelf seas. Benthic island (e.g. paleo-swells above the chemocline) allowed benthic organisms to survive. During phases of enhanced bottom water oxygenation benthic taxa resettled previous death zones. Paleo-ecosystems: Early Toarcian environmental crisis The Early Toarcian Carbon Isotope Excursion Paleo-ecosystems: Early Toarcian environmental crisis The Pliensbachian to Early Toarcian carbon isotope stratigraphy recoded a negative carbon isotope excursion (Toa-CIE) that has been recoded in coeval sediments around the globe. Local depositional-related processes, however, impacted on the expression of the Toa-CIE. The Toa-CIE was preceded by a CIE at the Pl-Toa-boundary. Paleo-ecosystems: Early Toarcian environmental crisis The Toa-CIE has been documented in marine and terrestrial organic matter as well as in marine carbonates attesting to a perturbation of the entire exchangeable carbon reservoir (data from Hesselbo et al., 2000). Paleo-ecosystems: Early Toarcian environmental crisis A negative shift has also been documented in biomolecules originated in marine taxa and in land plant-derived long-chain n-alkanes (Schouten et al., 2000; Xu et al., 2017). Data support a global carbon cycle perturbation affecting the marine as well as the atmospheric carbon reservoirs. Paleo-ecosystems: Early Toarcian environmental crisis Impact of local depositional conditions on the expression of the Toa-CIE in the sedimentary record. Changes in sedimentation were related to the local depositional setting and to (global?) sea level changes. Transgressive phases resulted in stratigraphic condensation, while regressive phase in erosive events. (see Pittet et al., 2014; Ruebsam et al., 2014; 2015) Paleo-ecosystems: Early Toarcian environmental crisis MTM power spectra for stacked organic carbon isotope record (Luxembourg + Yorkshire) and for the inorganic carbon isotope record from Peniche. Similar spectral peaks have been documented for both records attesting to a similar periodicity. Based on their frequency ratios spectral peaks can be linked to Milankovitch frequencies (LF bpf: low frequency band-pass filter). The presence of an orbitally-forced periodicity in both carbon isotope records indicated that changes in global carbon cycle were potentially associated with climate-sensitive carbon reservoirs. Paleo-ecosystems: Early Toarcian environmental crisis Statistical analysis (spectral analysis) confirmed the presence of a periodicity in carbon isotope data that can be associated with astronomical cycles (Milankovitch). Paleo-ecosystems: Early Toarcian environmental crisis Magnitude of the Toa-CIE: The Toa-CIE is associated with a decline in carbon isotope values that range from -3 to -7‰ . Changes in organo-facies (source/preservation of the sedimentary organic matter) can impact on carbon isotope values. Thus, a good correlation is seen for HI and carbon isotope values (Suan et al., 2015). Paleo-ecosystems: Early Toarcian environmental crisis Corrected for organic matter changes the Toa-CIE can be associated with a decline of about -3 to -4‰ (Suan et al., 2015). Paleo-ecosystems: Early Toarcian environmental crisis Mechanism proposed to explain the Toarcian CIE: - Recycling of 12C-enriched carbon in a stratified water column (Küspert, 1976) Toa-CIE not only evident in anoxic/euxinic sediments - Volcanic outgassing associated with the emplacement of the K-F-LIP (e.g. Brazier et al., 2016) isotopic composition of volcanic CO2 similar to atmospheric CO2, thus huge amounts of carbon would be required to explain a -3‰ negative CIE - Intrusion of magmatic dykes into Gondwana coals (Svensen et al., 2007) Orbitally-forced periodicity cannot be explained by carbon emission related to volcanism - Increased rates of wetland methanogeneis (Them II et al., 2017) fail
Load more

Recommended publications
  • A Model for the Oceanic Mass Balance of Rhenium and Implications for the Extent of Proterozoic Ocean Anoxia
    UC Riverside UC Riverside Previously Published Works Title A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia Permalink https://escholarship.org/uc/item/1gh1h920 Journal GEOCHIMICA ET COSMOCHIMICA ACTA, 227 ISSN 0016-7037 Authors Sheen, Alex I Kendall, Brian Reinhard, Christopher T et al. Publication Date 2018-04-15 DOI 10.1016/j.gca.2018.01.036 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Available online at www.sciencedirect.com ScienceDirect Geochimica et Cosmochimica Acta 227 (2018) 75–95 www.elsevier.com/locate/gca A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia Alex I. Sheen a,b,⇑, Brian Kendall a, Christopher T. Reinhard c, Robert A. Creaser b, Timothy W. Lyons d, Andrey Bekker d, Simon W. Poulton e, Ariel D. Anbar f,g a Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada b Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada c School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA d Department of Earth Sciences, University of California, Riverside, CA 92521, USA e School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK f School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA g School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA Received 13 July 2017; accepted in revised form 30 January 2018; available online 8 February 2018 Abstract Emerging geochemical evidence suggests that the atmosphere-ocean system underwent a significant decrease in O2 content following the Great Oxidation Event (GOE), leading to a mid-Proterozoic ocean (ca.
    [Show full text]
  • Cascading of Habitat Degradation: Oyster Reefs Invaded by Refugee Fishes Escaping Stress
    Ecological Applications, 11(3), 2001, pp. 764±782 q 2001 by the Ecological Society of America CASCADING OF HABITAT DEGRADATION: OYSTER REEFS INVADED BY REFUGEE FISHES ESCAPING STRESS HUNTER S. LENIHAN,1 CHARLES H. PETERSON,2 JAMES E. BYERS,3 JONATHAN H. GRABOWSKI,2 GORDON W. T HAYER, AND DAVID R. COLBY NOAA-National Ocean Service, Center for Coastal Fisheries and Habitat Research, 101 Pivers Island Road, Beaufort, North Carolina 28516 USA Abstract. Mobile consumers have potential to cause a cascading of habitat degradation beyond the region that is directly stressed, by concentrating in refuges where they intensify biological interactions and can deplete prey resources. We tested this hypothesis on struc- turally complex, species-rich biogenic reefs created by the eastern oyster, Crassostrea virginica, in the Neuse River estuary, North Carolina, USA. We (1) sampled ®shes and invertebrates on natural and restored reefs and on sand bottom to compare ®sh utilization of these different habitats and to characterize the trophic relations among large reef-as- sociated ®shes and benthic invertebrates, and (2) tested whether bottom-water hypoxia and ®shery-caused degradation of reef habitat combine to induce mass emigration of ®sh that then modify community composition in refuges across an estuarine seascape. Experimen- tally restored oyster reefs of two heights (1 m tall ``degraded'' or 2 m tall ``natural'' reefs) were constructed at 3 and 6 m depths. We sampled hydrographic conditions within the estuary over the summer to monitor onset and duration of bottom-water hypoxia/anoxia, a disturbance resulting from density strati®cation and anthropogenic eutrophication. Reduc- tion of reef height caused by oyster dredging exposed the reefs located in deep water to hypoxia/anoxia for .2 wk, killing reef-associated invertebrate prey and forcing mobile ®shes into refuge habitats.
    [Show full text]
  • Son of Perdition Free Download
    SON OF PERDITION FREE DOWNLOAD Wendy Alec | 490 pages | 01 Apr 2010 | Warboys Publishing (Ireland) Limited | 9780956333001 | English | Dublin, Ireland Who Is the Son of Perdition? The unembodied spirits who supported Lucifer in the war in heaven and were cast out Moses and mortals who commit Son of Perdition unpardonable sin against the Holy Ghost will inherit the same condition as Lucifer and Cain, and thus are called "sons of Son of Perdition. Contrasting beliefs. Recently Popular Media x. Verse Only. BLB Searches. So who is he? The bible describes the behavior of one who worships Jesus Christ. The purposes of the Son of Perdition oppose those of Jesus. A verification email has been sent to the address you provided. Blue Letter Bible study tools make reading, Son of Perdition and studying the Bible easy and rewarding. Extinction event Holocene extinction Human extinction List of extinction events Genetic erosion Son of Perdition pollution. Christianity portal. Re-type Password. Even a believer who maintains the faith can become discouraged and lose the peace of the Holy Spirit when he is cut off from the body of Christ. Biblical texts. By proceeding, you consent to our cookie usage. Back Psalms 1. The Son of Perdition is the progeny of abuse and desolation. Sort Canonically. The Millennium. No Number. Advanced Options Exact Match. However, scripture declares that "the soul can never die" Son of Perdition and that in the Resurrection the spirit and the body are united "never to be divided" Alma ; cf. Individual instructors or editors may still require Son of Perdition use of URLs.
    [Show full text]
  • Substantial Vegetation Response to Early Jurassic Global Warming with Impacts on Oceanic Anoxia
    ARTICLES https://doi.org/10.1038/s41561-019-0349-z Substantial vegetation response to Early Jurassic global warming with impacts on oceanic anoxia Sam M. Slater 1*, Richard J. Twitchett2, Silvia Danise3 and Vivi Vajda 1 Rapid global warming and oceanic oxygen deficiency during the Early Jurassic Toarcian Oceanic Anoxic Event at around 183 Ma is associated with a major turnover of marine biota linked to volcanic activity. The impact of the event on land-based eco- systems and the processes that led to oceanic anoxia remain poorly understood. Here we present analyses of spore–pollen assemblages from Pliensbachian–Toarcian rock samples that record marked changes on land during the Toarcian Oceanic Anoxic Event. Vegetation shifted from a high-diversity mixture of conifers, seed ferns, wet-adapted ferns and lycophytes to a low-diversity assemblage dominated by cheirolepid conifers, cycads and Cerebropollenites-producers, which were able to sur- vive in warm, drought-like conditions. Despite the rapid recovery of floras after Toarcian global warming, the overall community composition remained notably different after the event. In shelf seas, eutrophication continued throughout the Toarcian event. This is reflected in the overwhelming dominance of algae, which contributed to reduced oxygen conditions and to a marked decline in dinoflagellates. The substantial initial vegetation response across the Pliensbachian/Toarcian boundary compared with the relatively minor marine response highlights that the impacts of the early stages of volcanogenic
    [Show full text]
  • Molecular Biogeochemistry, Lecture 8
    12.158 Lecture Pigment-derived Biomarkers (1) Colour, structure, distribution and function (2) Biosynthesis (3) Nomenclature (4) Aromatic carotenoids ● Biomarkers for phototrophic sulfur bacteria ● Alternative biological sources (5) Porphyrins and maleimides Many of the figures in this lecture were kindly provided by Jochen Brocks, RSES ANU 1 Carotenoid pigments ● Carotenoids are usually yellow, orange or red coloured pigments lutein β-carotene 17 18 19 2' 2 4 6 8 3 7 9 16 1 5 lycopenelycopene 2 Structural diversity ● More than 600 different natural structures are known, ● They are derived from the C40 carotenoid lycopene by varied hydrogenation, dehydrogenation, cyclization and oxidation reaction 17 18 19 2' 2 4 6 8 3 7 9 16 1 5 lycopene neurosporene α-carotene γ -carotene spirilloxanthin siphonaxanthin canthaxanthin spheroidenone 3 Structural diversity Purple non-sulfur bacteria peridinin 7,8-didehydroastaxanthin okenone fucoxanthin Biological distribution ● Carotenoids are biosynthesized de novo by all phototrophic bacteria, eukaryotes and halophilic archaea ● They are additionally synthesized by a large variety of non-phototrophs ● Vertebrates and invertebrates have to incorporate carotenoids through the diet, but have often the capacity to structurally modifiy them 4 Carotenoid function (1) Accessory pigments in Light Harvesting Complex (LHC) (annual production by marine phytoplancton alone: 4 million tons) e.g. LH-II Red and blue: protein complex Green: chlorophyll Yellow: lycopene (2) Photoprotection (3) photoreceptors for phototropism
    [Show full text]
  • Effects of Natural and Human-Induced Hypoxia on Coastal Benthos
    Biogeosciences, 6, 2063–2098, 2009 www.biogeosciences.net/6/2063/2009/ Biogeosciences © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Effects of natural and human-induced hypoxia on coastal benthos L. A. Levin1, W. Ekau2, A. J. Gooday3, F. Jorissen4, J. J. Middelburg5, S. W. A. Naqvi6, C. Neira1, N. N. Rabalais7, and J. Zhang8 1Integrative Oceanography Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0218, USA 2Fisheries Biology, Leibniz Zentrum fur¨ Marine Tropenokologie,¨ Leibniz Center for Tropical Marine Ecology, Fahrenheitstr. 6, 28359 Bremen, Germany 3National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK 4Laboratory of Recent and Fossil Bio-Indicators (BIAF), Angers University, 2 Boulevard Lavoisier, 49045 Angers Cedex 01, France 5Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands 6National Institution of Oceanography, Dona Paula, Goa 403004, India 7Louisiana Universities Marine Consortium, Chauvin, Louisiana 70344, USA 8State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 Zhongshan Road North, Shanghai 200062, China Received: 17 January 2009 – Published in Biogeosciences Discuss.: 3 April 2009 Revised: 21 August 2009 – Accepted: 21 August 2009 – Published: 8 October 2009 Abstract. Coastal hypoxia (defined here as <1.42 ml L−1; Mobile fish and shellfish will migrate away from low-oxygen 62.5 µM; 2 mg L−1, approx. 30% oxygen saturation) devel- areas. Within a species, early life stages may be more subject ops seasonally in many estuaries, fjords, and along open to oxygen stress than older life stages. coasts as a result of natural upwelling or from anthropogenic Hypoxia alters both the structure and function of benthic eutrophication induced by riverine nutrient inputs.
    [Show full text]
  • Coupled Reductive and Oxidative Sulfur Cycling in the Phototrophic Plate of a Meromictic Lake T
    Geobiology (2014), 12, 451–468 DOI: 10.1111/gbi.12092 Coupled reductive and oxidative sulfur cycling in the phototrophic plate of a meromictic lake T. L. HAMILTON,1 R. J. BOVEE,2 V. THIEL,3 S. R. SATTIN,2 W. MOHR,2 I. SCHAPERDOTH,1 K. VOGL,3 W. P. GILHOOLY III,4 T. W. LYONS,5 L. P. TOMSHO,3 S. C. SCHUSTER,3,6 J. OVERMANN,7 D. A. BRYANT,3,6,8 A. PEARSON2 AND J. L. MACALADY1 1Department of Geosciences, Penn State Astrobiology Research Center (PSARC), The Pennsylvania State University, University Park, PA, USA 2Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA 3Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA 4Department of Earth Sciences, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA 5Department of Earth Sciences, University of California, Riverside, CA, USA 6Singapore Center for Environmental Life Sciences Engineering, Nanyang Technological University, Nanyang, Singapore 7Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany 8Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA ABSTRACT Mahoney Lake represents an extreme meromictic model system and is a valuable site for examining the organisms and processes that sustain photic zone euxinia (PZE). A single population of purple sulfur bacte- ria (PSB) living in a dense phototrophic plate in the chemocline is responsible for most of the primary pro- duction in Mahoney Lake. Here, we present metagenomic data from this phototrophic plate – including the genome of the major PSB, as obtained from both a highly enriched culture and from the metagenomic data – as well as evidence for multiple other taxa that contribute to the oxidative sulfur cycle and to sulfate reduction.
    [Show full text]
  • Ecosystems Mario V
    Ecosystems Mario V. Balzan, Abed El Rahman Hassoun, Najet Aroua, Virginie Baldy, Magda Bou Dagher, Cristina Branquinho, Jean-Claude Dutay, Monia El Bour, Frédéric Médail, Meryem Mojtahid, et al. To cite this version: Mario V. Balzan, Abed El Rahman Hassoun, Najet Aroua, Virginie Baldy, Magda Bou Dagher, et al.. Ecosystems. Cramer W, Guiot J, Marini K. Climate and Environmental Change in the Mediterranean Basin -Current Situation and Risks for the Future, Union for the Mediterranean, Plan Bleu, UNEP/MAP, Marseille, France, pp.323-468, 2021, ISBN: 978-2-9577416-0-1. hal-03210122 HAL Id: hal-03210122 https://hal-amu.archives-ouvertes.fr/hal-03210122 Submitted on 28 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future First Mediterranean Assessment Report (MAR1) Chapter 4 Ecosystems Coordinating Lead Authors: Mario V. Balzan (Malta), Abed El Rahman Hassoun (Lebanon) Lead Authors: Najet Aroua (Algeria), Virginie Baldy (France), Magda Bou Dagher (Lebanon), Cristina Branquinho (Portugal), Jean-Claude Dutay (France), Monia El Bour (Tunisia), Frédéric Médail (France), Meryem Mojtahid (Morocco/France), Alejandra Morán-Ordóñez (Spain), Pier Paolo Roggero (Italy), Sergio Rossi Heras (Italy), Bertrand Schatz (France), Ioannis N.
    [Show full text]
  • Uranium Isotope Evidence for Two Episodes of Deoxygenation During Oceanic Anoxic Event 2
    Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2 Matthew O. Clarksona,1,2, Claudine H. Stirlinga, Hugh C. Jenkynsb, Alexander J. Dicksonb,c, Don Porcellib, Christopher M. Moyd, Philip A. E. Pogge von Strandmanne, Ilsa R. Cookea, and Timothy M. Lentonf aDepartment of Chemistry, University of Otago, Dunedin 9054, New Zealand; bDepartment of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom; cDepartment of Earth Sciences, Royal Holloway University of London, Egham TW20 0EX, United Kingdom; dDepartment of Geology, University of Otago, Dunedin 9054, New Zealand; eLondon Geochemistry and Isotope Centre, Institute of Earth and Planetary Sciences, University College London and Birkbeck, University of London, London WC1E 6BT, United Kingdom; and fEarth System Science, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QE, United Kingdom Edited by Thure E. Cerling, University of Utah, Salt Lake City, UT, and approved January 22, 2018 (received for review August 30, 2017) Oceanic Anoxic Event 2 (OAE 2), occurring ∼94 million years ago, successions in many ocean basins. The preferential burial of iso- was one of the most extreme carbon cycle and climatic perturba- topically light carbon (C) also contributed to a broad positive carbon tions of the Phanerozoic Eon. It was typified by a rapid rise in isotope excursion (CIE) across OAE 2 that is utilized as a global atmospheric CO2, global warming, and marine anoxia, leading to chemostratigraphic marker of the event (1). Silicate weathering and the widespread devastation of marine ecosystems. However, the organic carbon burial are vital components of the global carbon cycle precise timing and extent to which oceanic anoxic conditions ex- and represent important negative feedback mechanisms that se- panded during OAE 2 remains unresolved.
    [Show full text]
  • Earth: Atmospheric Evolution of a Habitable Planet
    Earth: Atmospheric Evolution of a Habitable Planet Stephanie L. Olson1,2*, Edward W. Schwieterman1,2, Christopher T. Reinhard1,3, Timothy W. Lyons1,2 1NASA Astrobiology Institute Alternative Earth’s Team 2Department of Earth Sciences, University of California, Riverside 3School of Earth and Atmospheric Science, Georgia Institute of Technology *Correspondence: [email protected] Table of Contents 1. Introduction ............................................................................................................................ 2 2. Oxygen and biological innovation .................................................................................... 3 2.1. Oxygenic photosynthesis on the early Earth .......................................................... 4 2.2. The Great Oxidation Event ......................................................................................... 6 2.3. Oxygen during Earth’s middle chapter ..................................................................... 7 2.4. Neoproterozoic oxygen dynamics and the rise of animals .................................. 9 2.5. Continued oxygen evolution in the Phanerozoic.................................................. 11 3. Carbon dioxide, climate regulation, and enduring habitability ................................. 12 3.1. The faint young Sun paradox ................................................................................... 12 3.2. The silicate weathering thermostat ......................................................................... 12 3.3. Geological
    [Show full text]
  • DISCLAIMER the IPBES Global Assessment on Biodiversity And
    DISCLAIMER The IPBES Global Assessment on Biodiversity and Ecosystem Services is composed of 1) a Summary for Policymakers (SPM), approved by the IPBES Plenary at its 7th session in May 2019 in Paris, France (IPBES-7); and 2) a set of six Chapters, accepted by the IPBES Plenary. This document contains the draft Glossary of the IPBES Global Assessment on Biodiversity and Ecosystem Services. Governments and all observers at IPBES-7 had access to these draft chapters eight weeks prior to IPBES-7. Governments accepted the Chapters at IPBES-7 based on the understanding that revisions made to the SPM during the Plenary, as a result of the dialogue between Governments and scientists, would be reflected in the final Chapters. IPBES typically releases its Chapters publicly only in their final form, which implies a delay of several months post Plenary. However, in light of the high interest for the Chapters, IPBES is releasing the six Chapters early (31 May 2019) in a draft form. Authors of the reports are currently working to reflect all the changes made to the Summary for Policymakers during the Plenary to the Chapters, and to perform final copyediting. The final version of the Chapters will be posted later in 2019. The designations employed and the presentation of material on the maps used in the present report do not imply the expression of any opinion whatsoever on the part of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
    [Show full text]
  • Persistent Global Marine Euxinia in the Early Silurian ✉ Richard G
    ARTICLE https://doi.org/10.1038/s41467-020-15400-y OPEN Persistent global marine euxinia in the early Silurian ✉ Richard G. Stockey 1 , Devon B. Cole 2, Noah J. Planavsky3, David K. Loydell 4,Jiří Frýda5 & Erik A. Sperling1 The second pulse of the Late Ordovician mass extinction occurred around the Hirnantian- Rhuddanian boundary (~444 Ma) and has been correlated with expanded marine anoxia lasting into the earliest Silurian. Characterization of the Hirnantian ocean anoxic event has focused on the onset of anoxia, with global reconstructions based on carbonate δ238U 1234567890():,; modeling. However, there have been limited attempts to quantify uncertainty in metal isotope mass balance approaches. Here, we probabilistically evaluate coupled metal isotopes and sedimentary archives to increase constraint. We present iron speciation, metal concentration, δ98Mo and δ238U measurements of Rhuddanian black shales from the Murzuq Basin, Libya. We evaluate these data (and published carbonate δ238U data) with a coupled stochastic mass balance model. Combined statistical analysis of metal isotopes and sedimentary sinks provides uncertainty-bounded constraints on the intensity of Hirnantian-Rhuddanian euxinia. This work extends the duration of anoxia to >3 Myrs – notably longer than well-studied Mesozoic ocean anoxic events. 1 Stanford University, Department of Geological Sciences, Stanford, CA 94305, USA. 2 School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA. 3 Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA. 4 School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth PO1 3QL, UK. 5 Faculty of Environmental Sciences, Czech University of Life Sciences ✉ Prague, Prague, Czech Republic.
    [Show full text]